In the year 1990, Iqbal Haroon Khan (Jackie Shroff) runs The Great Indian Circus in Chicago, which has fallen on bad times. Anderson's (Andrew Bicknell) bank — Western Bank of Chicago —, which has lent money to Iqbal Khan, decides to close down the circus when Khan is unable to repay the loan. Young Sahir (Siddharth Nigam), the little son of Iqbal Khan, pleads with Anderson not to shut down his father's circus, as he and his father would soon be able to turn the corner. But Iqbal Khan's presenta
tion before the bankers and Sahir's pleas don't help. Iqbal Khan commits suicide in front of the heartless Anderson, leaving Sahir devastated.
Now in 2013, Sahir (Aamir Khan) has still not forgotten the high-handedness of the bank and swears revenge. He robs various branches of Western Bank of Chicago, leaving behind a message in Hindi and a clown mask. During the chase, he runs from top to the bottom of the Western Bank of Chicago building. As the police comes to the scene, he runs into a van as the they begin to surround the vehicle. Sahir jumps out in a BMW K1300R after a little explosion. On the chase, he slides under a truck and pops out to continue. He further kicks a police officer off his patrol motorcycle causing the officer to lose control and crash into a newspaper stand. While beyond that, Sahir continually tries to escape his pursuers and goes into a public parking garage. Then out of nowhere, he uses a steel cable cord like an attachment and rides his bike on it and is nearly knocked down by a train. despite all efforts of law enforcement, the robbery isn't foiled and he successfully gets away.
As Chicago Police Officer Victoria (Tabrett Bethell) fails to catch him, she calls ACP Jai Dixit (Abhishek Bachchan) and his partner, Ali (Uday Chopra), for help in solving the case. Jai baits Sahir into robbing again by making it known he's on the case and that he believes the thief to be an amateur thereby goading him on. Gathering information from a news channel regarding the plan, Sahir poses as an informant for Jai, and manages to gather information on the bank while giving Jai a lead to follow. Eventually, Sahir robs the bank and escapes, but Jai and Ali follow him. During the pursuit, Sahir nearly knocks Ali and stops on Warbash Avenue as the bridge rises, he drives straight and jumps off. His bike transforms into a jet ski. While on a water pursuit, Jai manages to take a boat and chases Sahir. After almost knocking off Ali, Sahir is almost about to reach the next bridge but the police arrive. Sahir dives underwater, then jumps out from the water ejecting his jet ski. Jai, while hanging on a helicopter ladder, manages to shoot Sahir on the left shoulder before he disappears again.
Sahir has a big premiere of a revamped version of The Great Indian Circus, with his female lead acrobat, Aaliya (Katrina Kaif), involving a trick with him disappearing in one place and showing up in another. The show is a success, but afterwards, Jai, Ali, and the police surround him, knowing he's the thief. Jai says the proof will be the gunshot wound, but when Sahir is examined, there is no evidence of a gunshot wound anywhere on his body. Jai and Ali leave while Sahir retires to his dressing room. It is then revealed that Sahir has an autistic twin brother, Samar, who helps him pull off his trick and helps him in planning and pulling of the robberies (like the rope string stunt and ejecting the jet-ski bike) and it was Samar who sustained the gun-shot wound.
Jai is fired from the case, but is encouraged by Ali to prove Sahir's guilt by going rogue. Jai eventually finds out about Samar, and sets about finding a way to corner Sahir. Samar, being mentally challenged, is kept in seclusion by Sahir. However, he allows Samar outdoors once a week, and Jai manages to befriend him during this time in order to perform his plan. Samar has fallen in love with Aaliya after performing with her in the circus, but cannot express it. This leads to a rift between the brothers. Jai tries to take advantage of this, but Sahir finds out and thwarts Jai's plan to stop them.When Sahir comes in the disguise of Samar, Jai reveals his true identity and assuming him to be Samar, tells him to surrender since he can give them justice.When Sahir reveals himself, he ties Jai to the track of a roller coaster and tells him that he used Samar for his own benefit. He switches the roller coaster on but Ali arrives in time to save him from being crushed. He decides the only way to catch the brothers is in the act of robbing. Sahir and Samar pull off their final bank heist, and escape. However, the following day, Jai manages to corner them as they're making their way out of town. They rob on 22 May. Samar is hesitant to run when Aaliya shows up, begging him to stop. Sahir surrenders to Jai, asking him to spare Samar. Jai agrees, but right after, Sahir attempts to jump off the dam. Samar grabs Sahir's hand, refusing to let him go. Sahir begs Samar to let go, saying he can live freely with Aaliya. But Samar says that both of them are born together and should die together. Eventually, the two of them jump off the dam together. Western Bank of Chicago is shut down as a result of the heists, while Aaliya is shown having taken over The Great Indian Circus and still performing for it